Robotic induction in materials handling facilities with batch singulation

ABSTRACT

Methods and apparatus for robotic induction in materials handling facilities with batch singulation inventory areas are disclosed. A control system directs the one or more robotic devices to transport a particular portable storage unit of a plurality of portable storage units to and from a particular induction station of one or more induction stations. The control system directs induction of one or more single units of items from one or more locations of the portable storage unit, while the particular portable storage unit is located at an induction station, into the conveyance mechanism at the particular induction station. The control system directs picks of batches of heterogeneous items from a separate inventory storage area. The control system directs induction of single units of items from the batches of heterogeneous items picked from the separate inventory storage area into the conveyance mechanism at a batch singulation station.

This application is a continuation of U.S. application Ser. No.12/981,109, filed Dec. 29, 2010, now U.S. Pat. No. 8,798,784, which ishereby incorporated by reference in its entirety.

BACKGROUND

In a distribution system, a retailer or other product distributor (whichmay collectively be referred to as distributors) typically maintains aninventory of various items at one or more distribution centers,fulfillment centers, cross-docking facilities, materials handlingfacilities or warehouses (which may collectively be referred to asmaterials handling facilities). The inventory items are ordered from oneor more vendors, received at the materials handling facilities asinbound shipments, and stocked in inventory of the materials handlingfacilities. In a conventional order fulfillment process, orders foritems may be received from customers of the distributor. Units of theordered items are picked from various locations in the inventory in thematerials handling facilities, processed for shipping, and shipped asoutbound shipments to the customers.

An example conventional order fulfillment process may include a pickprocess and a sortation process in which mixed batches of units pickedfor orders are sorted into their respective orders. In a conventionalorder fulfillment process, requests (e.g., orders) for items fromrequestors may be divided among multiple pickers, who then pick mixedbatches of items. The orders may be subdivided among the pickers;therefore, two or more of the pickers may pick items for one order.Consequently, a sort operation to select the proper units of items forgiven orders from the aggregations of units items returned by eachrespective picker is required. Conventionally, sorting may be performedusing automated sorting mechanisms or manual sorting systems. Automatedsorting mechanisms for sorting certain types of inventory itemsaccording to individual orders include, but are not limited to, theCrisplant® sorter, Eurosort® sorters, and automated sorting mechanismsoffered by other vendors. Using an automated sorting mechanism, batchesor a stream of incoming picked items for multiple different customerorders are received at the automated sorting mechanism and sorted by theautomated mechanism according to individual orders.

In typical automated sorting mechanisms, individual units of items areinducted from picked batches of mixed items directly onto the sortationmechanism into carriers (e.g., tilt trays) that are fixed to thesortation mechanism. Thus, typical automated sorting mechanisms that areused in materials handling facilities tend to be linear sorting systems.Linear sorting inducts or places individual units of items from pickedbatches of items (referred to as singulation) onto an individual tray ortransport mechanism that is a fixed component of a linear piece ofautomated equipment. All of the trays or transport mechanisms areconnected in a linear sequence (typically in a circle or ovalcontinuously-running loop). An item is placed directly onto a carrier ofthe automated sorting mechanism. Linear sorting systems thus tend to belimited in velocity, total capacity, and the size and types of itemsthat can be sorted.

Robotics in Order Fulfillment Systems

Order fulfillment systems exist in which mobile robotic devices areemployed. In a conventional order fulfillment system that employsrobotic devices, an order fulfillment center includes one or moreworkstations. An operator at each workstation is assigned a set of oneor more orders to fulfill from inventory; typically, four to twentyorders are assigned to a workstation in a set. To fulfill the currentset of orders at a given workstation, the mobile robotic devices pick upand deliver portable inventory storage units from a stock storage areato the work station, where the operator picks items from the storageunit and places the items into shipping boxes or slots assigned toparticular orders in the current set. The mobile robotic devices delivershelving units to the workstation until all of the orders in the currentset of orders assigned to the work station are fulfilled from inventory.At that time, the fulfilled orders are moved from the workstation todownstream stations where the shipping boxes are sealed and shipped, anda new set of boxes or slots for a new set of orders is moved to theworkstation to start the process over again.

The conventional order fulfillment system employing robotic devicesdescribed above is serialized; all inventory for a particular order hasto come to a particular workstation that is assigned that order. In suchconventional systems, the number of workstations required and thereforethe capacity of the system is tied to how quickly (cycle time) all itemsfor an order can be delivered to the workstation from the time an orderis assigned to a particular workstation and the time the last item forthe order is pulled from a storage units at the workstation. Thus, thedelivery of inventory to a workstation quickly and without delay iscritical to the success of the conventional system. Orders at aworkstation may have to wait for fulfillment while needed inventorystorage units are being delivered to and processed at one or more otherworkstations. This is particularly the case where a given storage unitmay store many different types of items, as the likelihood that two ormore workstations may need the same storage unit at the same time goesup as the number of types on the storage unit increases. Particularorders can be delayed waiting for inventory if the size of the inventorystorage area is very large as inventory must travel to a specificworkstation to be fulfilled regardless of distance traveled. To maintainefficiency, this conventional robotic order fulfillment system mayrequire frequent tuning, for example by rearranging the distribution ofitems or storage units in inventory storage, in attempts to minimize themovements of the robotic devices and thus maximize throughput of thesystem. This optimization may be effective when few types of units arestored in inventory (e.g., thousands) and there are large quantities ofeach unit type (e.g., hundreds/thousands) but ineffective when manytypes of units (e.g., hundreds of thousands/millions) and few units(e.g., tens/hundreds) of each are stored. This large number of unittypes with few units of inventory each increases the odds a storage unitcould be required at any given workstation to fulfill an order. Thislack of optimization creates longer cycle times which require moreworkstations which create more competing demands for inventory storageunits which reduce cycle times and therefore creates a downward spiralof system throughput once this condition occurs. While this conventionalrobotic order fulfillment system may work well for single-floor,relatively small distribution centers (up to 100 k-200 k square feet)with relatively few types of items, the system is difficult to scale tolarger distribution centers (200 k+ square feet), distribution centerswith tens of thousands to millions of types of items, and multi-leveldistribution centers. In addition, this conventional robot-assistedorder fulfillment system is an end-to-end order fulfillment solution,and is difficult to integrate with other materials handling techniquesresulting in reduced flexibility and increased costs when supportingnon-level system demand.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a logical representation or view of the operation of amaterials handling facility in which embodiments of methods andapparatus for robotic induction may be implemented.

FIG. 2A shows a logical representation or view of the operation of amaterials handling facility that includes two separate inventory areasin which the picking process including robotic induction is implemented.

FIG. 2B shows a logical representation or view of the operation of amaterials handling facility in which the picking process includingrobotic induction is used in combination with another, different pickingprocess.

FIG. 3 illustrates an example of a physical layout of a materialshandling facility, such as an order fulfillment facility or center, inwhich embodiments of the robotic induction technique may be implemented.

FIG. 4 shows an example inventory area in which there are two stockstorage areas in an inventory area, with a row of induction stationsbetween the stock storage areas, according to some embodiments.

FIGS. 5A and 5B illustrate an example mobile robotic device (bot) thatmay be used in at least some embodiments.

FIGS. 6A and 6B illustrate an example storage unit that may be used inat least some embodiments.

FIG. 7 illustrates an example bot with a storage unit, according to atleast some embodiments.

FIG. 8 illustrates an example physical layout of a materials handlingfacility, such as an order fulfillment facility or center, in whichembodiments of the robotic induction technique as described herein maybe implemented as part of a non-linear, unit-level materials handlingsystem.

FIG. 9 illustrates an example conveyance receptacle, according to atleast some embodiments.

FIG. 10 illustrates operation of an example induction station accordingto at least some embodiments.

FIG. 11 illustrates operation of an example sorting station that may beused in embodiments of a non-linear, unit-level materials handlingsystem.

FIG. 12 is a flowchart illustrating a method for robotic induction in amaterials handling facility, according to at least some embodiments.

FIG. 13 is a flowchart illustrating a method of operation in anon-linear, unit-level materials handling system in which an embodimentof the robotic induction technique is implemented, according to at leastsome embodiments.

FIG. 14 is a block diagram illustrating an example computer system thatmay be used in at least some embodiments.

While embodiments are described herein by way of example for severalembodiments and illustrative drawings, those skilled in the art willrecognize that embodiments are not limited to the embodiments ordrawings described. It should be understood, that the drawings anddetailed description thereto are not intended to limit embodiments tothe particular form disclosed, but on the contrary, the intention is tocover all modifications, equivalents and alternatives falling within thespirit and scope as defined by the appended claims. The headings usedherein are for organizational purposes only and are not meant to be usedto limit the scope of the description or the claims. As used throughoutthis application, the word “may” is used in a permissive sense (i.e.,meaning having the potential to), rather than the mandatory sense (i.e.,meaning must). Similarly, the words “include,” “including,” and“includes” mean including, but not limited to.

DETAILED DESCRIPTION OF EMBODIMENTS

Various embodiments of methods and apparatus for robotic induction inmaterials handling facility processes such as order fulfillmentprocesses are described. In embodiments, one or more induction stationsare located in an inventory area. The induction stations performsingulation and induction; that is, singulation of inventory into singleunits of items and induction of the units of items into a conveyancemechanism. The inventory area includes a stock storage area thatcontains a plurality of portable storage units, each storage unitincluding one or more locations for stowing inventory, with eachlocation typically, but not necessarily, stowing one type of item.Mobile robotic devices (referred to herein as bots) are deployed todeliver particular storage units from the stock storage area toparticular induction stations. At the induction stations, human orautomated inductors perform singulation and induction of items from thestorage units into a conveyance mechanism. To perform singulation andinduction, the inductors remove single units of items from locations onthe storage units and induct the single units of items into a conveyancemechanism. The conveyance mechanism delivers the single units of itemsto one or more downstream processing stations or devices, such assorting stations or sorting devices. One or more units of items of oneor more types of items for one or more customer orders may be singulatedand inducted from a given storage unit at an induction station; when thestation is done with a storage unit, the bot moves the storage unit fromthe induction station back to stock storage or to another inductionstation, and another bot moves a next storage unit to the inductionstation.

In some embodiments, to perform singulation and induction, the inductorsremove single units of items from the storage units and place the singleunits of items into conveyance receptacles (induction). Only one unit isplaced in each conveyance receptacle (singulation). The conveyancereceptacles are on, or are inducted into, the conveyance mechanism,which delivers the conveyance receptacles, each including a single unitof an item to the one or more downstream processing stations or devices.In other embodiments, to perform singulation and induction, theinductors remove single units of items from the storage units and placethe single units of items directly onto the conveyance mechanism(singulation and induction).

The operations of the bots, induction stations, conveyance mechanism,and downstream processing may be controlled and/or directed by amaterials handling facility control system. In an order fulfillmentprocess, the control system may receive orders, and direct theprocessing of items to fulfill the orders according to the roboticinduction method described above. However, unlike the conventional orderfulfillment system employing robotic devices described above in whichworkstations are assigned sets of orders to fulfill, the inductionstations are not assigned particular orders. The control system does notassign a given order to a particular induction station; instead, thecontrol system may direct bots to deliver storage units to two or moreinduction stations to fulfill a given order. Any item for any order canbe singulated and inducted into the conveyance mechanism at anyinduction station. Thus, an order does not have to wait at a workstationfor a particular type of item to be delivered to the station, as may bethe case in the conventional system described above.

The method for robotic induction in a materials handling facility isscalable to handle the needs of larger materials handling facilities(200 k+ square feet), materials handling facilities with tens ofthousands to millions of types of items, and multi-level materialshandling facilities. A materials handling facility can be implementedthat includes two or more inventory areas, for example an inventory areaon each level of a multi-level facility, with each inventory areaincluding one or more stock storage areas, one or more inductionstations, and a set of bots that operate within the inventory area. Insome implementations, an inventory area may be subdivided into zones,for example a zone of the stock storage area corresponding to (andnearby) each induction station, and one or more bots may be assigned tooperate within each zone. Inventory areas and/or zones may be added,removed, consolidated, or subdivided to adapt to changes in demand.Types of items may be, but are not necessarily, distributed among two ormore storage units in an inventory area so that the same type of itemcan be delivered to two or more induction stations at the same time. Inaddition, types of items may be, but are not necessarily, distributedamong two or more different inventory areas. A conveyance mechanism ormechanisms may serve each inventory area and zone; the conveyancemechanisms may merge outside the inventory areas for consolidateddownstream processing, or may deliver the singulated items fromdifferent inventory areas to different downstream processing locations.The control system may direct, control, and coordinate the orderfulfillment process across the two or more inventory areas, two or moreconveyance mechanisms, and the two or more downstream processinglocations.

Bots may be added to or removed from a given inventory area to handlechanges in demand. For example, one or more bots may be directed by thecontrol system to move from one inventory area to another inventory areato support an increase in demand in the first inventory area if thesecond inventory area has bots that are underutilized.

Embodiments of the method for robotic induction in a materials handlingfacility may be integrated with other materials handling techniques. Forexample, some orders or portions of orders may be fulfilled via adifferent picking and/or induction process; a stream of items from thedifferent picking and/or induction process may be merged with the streamof items from the method prior to or during downstream processing.

Embodiments of the method for robotic induction in a materials handlingfacility may, for example, be implemented in a non-linear, unit-levelmaterials handling system as illustrated in FIG. 8 that includes asortation system that employs sorting stations as illustrated in FIG.11. However, embodiments of the method for robotic induction in amaterials handling facility may be implemented in other materialshandling systems that employ other downstream processing techniquesincluding but not limited to other downstream sorting techniques; thedownstream sorting techniques may include automated sorting mechanismsand/or manual sorting systems.

FIG. 1 shows a logical representation or view of the operation of amaterials handling facility in which embodiments of methods andapparatus for robotic induction in a materials handling facility may beimplemented. For example, this Figure may illustrate an orderfulfillment center of a product distributor. Multiple customers 10 maysubmit orders 20 to the product distributor, where each order 20specifies one or more items from inventory 32 to be shipped to thecustomer that submitted the order. To fulfill the customers' orders 20,the items specified in the orders 20 may be retrieved, or picked, frominventory 32 (which may also be referred to as stock storage) in thematerials handling facility according to a picking process 30 asdescribed herein. In the picking process 30, under direction of acontrol system, storage units, each storing one or more units of one ormore types of items, may be automatically moved from inventory 32 toparticular induction stations, for example using robotic devices thatcan pick up and move storage units under direction of the controlsystem. At the induction stations, singulating induction 34 isperformed, manually or automatically, under direction of the controlsystem. In the singulating induction process 34, at an inductionstation, individual units of items are removed from one or morelocations on a given storage unit, delivered to the induction station bya robotic device (referred to herein as a “bot”), and the individualunits of items are inducted into the conveyance mechanism.

In some embodiments, in the singulating induction process 34, theindividual units of items may be placed into and associated withparticular conveyance receptacles. Only one unit is placed in eachconveyance receptacle. The conveyance receptacles are on, or areinducted into, the conveyance mechanism. In these implementations, thecontrol system may track and direct the conveyance receptacles in thematerials handling facility, for example using bar codes or otherreceptacle identifiers attached to or integrated in the receptacles andassociated with the units of items contained therein, to track anddirect the units of items associated with the conveyance receptacles.Receptacles, as used herein, may include, but are not limited to, anytote, basket, box, tray, or similar mechanism configured to receiveindividual units of items or batches of units of items in a materialshandling facility. In at least some embodiments, the conveyancereceptacles are not fixed to any conveyance mechanism, and thusconveyance receptacles can be added to or removed from a conveyancemechanism.

In some embodiments, instead of using conveyance receptacles in thesingulating induction process 34, single units of items are removed fromthe storage units and place directly onto the conveyance mechanism. Inthese embodiments, the control system may directly track and direct theunits of items on the conveyance mechanism. For example, in someimplementations, each unit of item inducted into the conveyancemechanism may have a unique unit identifier associated with theparticular unit, for example via a bar code, RFID tag, or otheridentifying mark or tag attached to or integrated with the unit of item.The control system may track and direct the units of items in thematerials handling facility using the unit identifiers of the units ofitems. As another example, in some implementations, one or more physicalcharacteristics of the items may be used to track and direct the unitsof items. For example, the materials handling facility may includecameras coupled to the control system whereby the control systemvisually identifies, tracks, and directs the individual units of itemsaccording to identifiable visual characteristics of the items.

A type of item held in inventory 32 may be referred to herein as simplyan item. The term unit may be used to refer to one instance of a type ofitem. However, cases, boxes, bundles, or other collections of instancesof items may be considered as units. The units of items in a collectionmay all be of the same type of item, for example a case of 12 instancesof a particular item, or may be a collection of one or more instances ofeach of two or more heterogeneous items. A collection of instances ofitem(s) (e.g., a case containing 12 instances of an item, or a bundlecontaining one or more instances of each of two or more heterogeneousitems, such as a boxed or bundled set of three different books) may thusbe considered or treated as a “unit” in the order fulfillment process.Thus, at induction stations, in addition to singulating and inductingindividual instances of items, collections of instances of item(s)designated as units may be singulated and inducted. Therefore,collections of instances of item(s) that are designated as units may besingulated and inducted into the conveyance mechanism at the inductionstations as well as individual instances of items.

When an induction station is done with a particular storage unit, thestorage unit may be automatically returned from the induction station toinventory 32, for example using a robotic device. A next storage unit,which may be staged nearby, may then be moved into place at theinduction station so that units may be selected from the storage unitand inducted into the conveyance mechanism.

The singulated and inducted units of items may be conveyed, by theconveyance mechanism to one or more stations in the materials handlingfacility for downstream processing, for example sorting 50 into theirrespective orders, packing 60, and finally shipping 70 to the customers10. In downstream processing, the units of items may be routed toparticular destinations for the units of items in accordance with therequests (orders) currently being processed, for example to sortingstations or to packing stations, under direction of the control system.An example sorting process and sorting station that may be a destinationfor the units of items is described later in this document.

Note that a picked, packed and shipped order does not necessarilyinclude all of the items ordered by the customer 10; an outgoingshipment to a customer 10 may include only a subset of the ordered itemsavailable to ship at one time from one inventory-storing location.

A materials handling facility may also include a receiving 80 operationfor receiving shipments of stock from one or more sources (e.g.,vendors) and for stowing the received stock into stock storage(inventory 32). The receiving 80 operation may also receive and processreturned purchased or rented items or orders from customers. At leastsome of these returned items are typically returned to inventory 32.

In at least some embodiments, rather than stowing directly to inventory32 as shown in FIG. 1, received inventory may be delivered to one ormore stowing stations (not shown). Under direction of the controlsystem, storage units may be automatically moved from inventory 32 toparticular stowing stations, for example using the robotic devices. Atthe stowing station(s), the received inventory may be manually orautomatically placed in locations on the storage units under directionof the control system. The storage units are then returned from thestowing station(s) to inventory 32, for example using the roboticdevices. In some embodiments, induction and stowing may be combined atone station so that individual items for orders can be inducted into theconveyance mechanism from storage units for delivery to one or moredownstream processing stations (e.g., sorting stations) and receiveditems can be stowed to the same storage units prior to the storage unitsbeing returned to inventory 32; storage units may also be moved frominventory 32 to the induction/stowing station(s) specifically forstowing.

The various operations of a materials handling facility may be locatedin one building, or alternatively may be spread or subdivided across twoor more buildings. In addition, a materials handling facility mayinclude one or multiple levels or floors. For example, a materialshandling facility that includes inventory 32 may include one, two, ormore levels; in multi-level facilities, inventory 32 may be spreadacross two or more levels. The total floor space of a materials handlingfacility may be anywhere from tens of thousands of square feet to morethan a million square feet, although embodiments may be implemented insmaller facilities.

The picking process 30 as illustrated in FIG. 1 may be implemented intwo or more different inventory areas, for example on different floorsor in different areas of a materials handling facility. FIG. 2A shows alogical representation or view of the operation of a materials handlingfacility that includes two separate inventory areas in which the pickingprocess including robotic induction is implemented. Two or more separatestock storage areas may be maintained, for example inventory 32A andinventory 32B. For example, the separate stock storage areas may belocated on different floors of a materials handling facility. For eachseparate stock storage area, there may be one or more associatedinduction stations. Types of items may be, but are not necessarily,stored in different stock storage areas. For example, units of a giventype of item may be stowed to locations in storage units in bothinventory 32A and inventory 32B.

To fulfill the customer orders 20, a portion of the orders 20, or partsof orders 20, may be directed to the picking process in each stockstorage area (picking 30A and 30B, in this example) by the controlsystem. Picking process 30A and 30B may operate as described above forpicking process 30 in reference to FIG. 1. In at least someimplementations, the stream of units of items that are singulated andinducted according to picking process 30A may be combined with thestream of units of items that are singulated and inducted according topicking process 30B prior to downstream processing 100.

The picking process 30 as illustrated in FIG. 1 may be used incombination with other picking processes. FIG. 2B shows a logicalrepresentation or view of the operation of a materials handling facilityin which the picking process is used in combination with another,different picking process. Two or more separate stock storages may bemaintained, for example inventory 32 and inventory 42. Picking process30 may operate as described above in reference to FIG. 1. Referring toFIG. 2B, to fulfill the customer orders 20, a portion of the orders 20,or parts of orders 20, may be directed to different picking process 40from inventory 42 under direction of the control system. In an examplepicking process 40 that may be used in some implementations, collectionsof items specified in the orders 20 may be directly retrieved or pickedfrom inventory 42 in the materials handling facility and placed intopick totes and/or pick carts as indicated at 44, by pickers underdirection of the control system. For example, pick totes may be used ina picking method in which multiple pickers pick the same batch. In thispicking method, the pickers may carry or otherwise convey pickreceptacles, referred to as totes, in inventory 42 area into which thepicked items are placed; heterogeneous units of items for differentorders may be placed into the same pick tote. Alternatively, pick cartsmay be used in a picking method in which a single picker picks an entirebatch. In this picking method, the pickers may convey pick carts ininventory 42 area into which the picked items are placed; heterogeneousunits of items for different orders may be placed into the same pickcart. The pick totes and/or carts containing collections or batches ofitems picked according to picking process 40 may be delivered orconveyed to one or more stations in the materials handling facility fordownstream processing 100, for example for sorting into their respectiveorders, packing, and shipping to the respective customers. The stream ofunits of items that are singulated and inducted according to pickingprocess 30 may be combined with the stream of units of items pickedaccording to the different picking process 40 during downstreamprocessing 100; the combining of the two streams of picked items mayoccur prior to or at sorting, prior to or at packing, or prior to or atshipping. In some embodiments, to combine the two streams prior to orduring downstream processing 100, the collections of units of itemspicked from inventory 42 in picking process 40 may be singulated andinducted into the conveyance mechanism to which the units of items areinducted in picking process 30, or into a separate conveyance mechanism.For example, in at least some implementations, the collections orbatches of heterogeneous items picked according to picking process 40may be delivered to a batch singulation station, where single units ofitems are selected from the collections or batches and inducted into theconveyance mechanism, under direction of the control system. In someimplementations, the units of items selected from the batches may beassociated with and placed in conveyance receptacles at the batchsingulation station; the conveyance receptacles are inducted into theconveyance mechanism. In other implementations, the units of itemsselected from the batches may inducted directly into the conveyancemechanism at the batch singulation station.

FIG. 3 illustrates an example of a physical layout of a materialshandling facility, such as an order fulfillment facility or center, inwhich embodiments of the robotic induction technique may be implemented.The number, relative size, and arrangement of elements in FIG. 3 aregiven by way of example, and are not intended to be limiting. Orderfulfillment center 200 may include one or more inventory 210 areas. Eachinventory 210 area includes a stock storage 214 that includes aplurality of storage units 220. Each storage unit 220 may include one ormore locations (e.g., slots, shelves, partitions, bins, etc.) in whichunits of items are stowed. Each storage unit 220 may stow one or moredifferent types of items. Storage unit 220 may be arranged two-deep inrows of two or more, with aisles between the rows, as illustrated, ormay be otherwise arranged.

Each inventory 210 area also includes one or more induction stations212. In this example, inventory 210 area includes six induction stations212, with three induction stations arranged on each side of the stockstorage 214 as induction stations 212A and induction stations 212B. Aconveyance mechanism 240 passes through or by each induction station212. FIG. 3 shows two separate conveyance mechanisms 240A and 240B, withconveyance mechanism 240A serving induction stations 212A and conveyancemechanism 240B serving induction stations 212B. In at least someimplementations, a conveyance mechanism may form a loop that passesthrough inventory 210 area, and out to one or more downstream processingareas or stations, and then back to inventory 210 area. In this example,conveyance mechanisms 240A and 240B are shown as going from inventory210 area to sorting 250, and from sorting 250 back to inventory 210area. FIG. 10 illustrates operations at an example induction station212.

At any one time, one or more bots 222 may be moving storage units 220from stock storage 214 area to induction stations 212 to fulfillportions or all of one or more requests or orders, under direction ofcontrol system 290. In at least some embodiments, to move a storage unit220, a bot 222 may move under the storage unit 220, lift the storageunit 220, and then move the storage unit 220 to a destination (e.g., aparticular induction station 212) under direction of control system 290.FIG. 3 shows several examples of bots with storage units 224. Forexample, FIG. 3 shows bot with storage unit 224A moving from stockstorage 214 towards an induction station 212A, bot with storage unit224B at an induction station 212A, and bot with storage unit 224C movingfrom an induction station 212B to stock storage 214. FIGS. 5A and 5Billustrate an example bot, FIGS. 6A and 6B illustrate an example storageunit, and FIG. 7 illustrates an example bot with storage unit.

At an induction station 212, in a singulation and induction process, aninductor 214 pulls units of items from locations on storage units 220,under direction of control system 290 and inducts the individual unitsof items into a conveyance mechanism 240. In some implementations,individual units of items are associated with and placed into particularconveyance receptacles on a conveyance mechanism 240 by the inductor214, under direction of control system 290 (induction). A single unit isplaced in each conveyance receptacle (singulation). FIG. 9 illustratesan example conveyance receptacle. In other implementations, theindividual units of items may be inducted directly into a conveyancemechanism 240 without placing the units of items into a conveyancereceptacle. An inductor 214 may be a human agent of the materialshandling facility, or may be an automated mechanism controlled bycontrol system 290.

In at least some embodiments, in addition to singulating and inductingunits of items from storage units 220 moved to induction stations 212 bybots 222 under direction of control system 290, some types of items, forexample fast-moving items, may be picked directly from inventory locatedat an induction station 212. For example, a pallet or other containercontaining units of a type of item may be delivered directly fromreceiving 280 or some other location to an induction station 212 by abot 222 or by some other mechanism, and the inductor 214 may then pickunits of the item directly from the container at the station 212 andinduct the picked units into the conveyance mechanism 240, underdirection of the control system 290.

The singulated and inducted units of items may then be delivered frominventory 210 area to a downstream processing station via the conveyancemechanism 240. During downstream processing, the units of items may beprocessed at a station, for example sorted into their respective ordersat a sorting 250 station under direction of the control system 290. Oncethe processing of items for an order is completed at a station, theitems may be delivered to another station for further processing, forexample to another sorting station to be sorted into orders, or to apacking station to be packaged for shipping 270. In someimplementations, units of items that are picked, singulated, andinducted for orders that specify multiple items may be routed by thecontrol system 290 via a conveyance mechanism 240 to a sorting 250station for sorting into their respective orders, while units of itemsthat are picked, singulated, and inducted for orders that specify onlythat single unit of that item (i.e., single-item orders) may be routedby the control system 290 via a conveyance mechanism 240 directly tosome other order processing station 260, such as a packing station.

In at least some embodiments, the conveyance mechanism(s) 240, underdirection of control system 290, may deliver the singulated units ofitems from inventory 210 area to sorting 250. Sorting 250 may includeone or more sorting stations where the units of items are removed fromthe conveyance mechanism(s) 240 and sorted into their respective ordersunder direction of control system 290. In at least some embodiments,conveyance mechanism 240 may deliver particular singulated units ofitems to particular sorting stations (or to other stations) underdirection of control system 290. Operations of an example sortingstation that may be used in some implementations is shown in FIG. 11.Sorted orders may be conveyed from sorting 250 station(s) to one or moreother order processing 260 stations for additional processing prior toshipping 270. Note that portions of a given order may be received at asorting 250 station or at an order processing station 260 at differenttimes, so processing at a downstream processing station may have to waitfor one or more items for some orders to be delivered to the stationfrom another station before completion of processing of the orders atthe station.

An order fulfillment center may also include one or more receiving 280operations or areas for receiving shipments of stock from variousvendors. Received stock may be placed into stock storage 214 in one ormore inventory 250 areas. The receiving 280 operation may also receiveand process returned, purchased, or rented items from customers. Atleast some of these items may be restocked into an inventory 250 area.

In at least some embodiments, rather than stowing directly to stockstorage 314 as shown in FIG. 3, received inventory may be delivered toone or more stowing stations (not shown). Under direction of the controlsystem 290, storage units 220 may be automatically moved from stockstorage 214 to particular stowing stations, for example using the bots222. At the stowing station(s), the received inventory may be manuallyor automatically placed in locations on the storage units 220 underdirection of the control system 290. The storage units 214 are returnedfrom the stowing station(s) to stock storage 314, for example using thebots 222. In some embodiments, induction and stowing may be combined atone or more of the induction stations 212 so that individual items fororders can be inducted into a conveyance mechanism 240 from storageunits 220 for delivery to one or more downstream processing stations(e.g., sorting stations) and received items can be stowed to the samestorage units 220 prior to the storage units 220 being returned to stockstorage 214. Storage units 214 may also be moved from stock storage 214to the induction/stowing station(s) specifically for stowing.

The various areas, operations and stations of an order fulfillmentcenter 200 may be located in one building or facility, or alternativelymay be spread or subdivided across two or more buildings or facilities.In addition, an order fulfillment center 200 may include one or multiplelevels or floors. For example, an order fulfillment center 200 mayinclude one, two, or more levels; in multi-level order fulfillmentcenters 200, a separate inventory 210 area may located on each of two ormore levels, and various downstream processing stations may be locatedon one or more of the levels.

The configuration of order fulfillment center 200, including theconfiguration of inventory 210 area and conveyance mechanism 240, asshown in FIG. 3 is given by way of example, and is not intended to belimiting. Other configurations for order fulfillment center 200,inventory 210 area, and conveyance mechanism(s) 240 are possible andcontemplated. As an example, FIG. 4 shows an example inventory 210 areain which there are two stock storage areas (stock storage 214A and stockstorage 214B) in an inventory 210 area, with a row of four inductionstations 212 running down the middle of inventory 210 area between stockstorage 214A and stock storage 214B, and with a single conveyancemechanism 240 serving all of the induction stations 212. As anotherexample (not shown), an inventory area may include induction stationsrunning down the middle of the inventory area as shown in FIG. 4, andalso induction stations on the sides of the inventory area as shown inFIG. 3.

In addition, a materials handling facility may include two or moreinventory 210 areas, which may be similarly or differently configured. Amaterials handling facility may, for example, have two or more levels,with a separate inventory 210 area located on at least two differentlevels. In these configurations, bots 222 may be directed, eitherautomatically by control system 290 or by operator input to the controlsystem 290, from one inventory 210 area to another inventory 210 area.For example when a first inventory 210 area has high demand and needsmore bots 222, while a second inventory 210 area has less demand and canspare at least one bot 222, at least one bot 222 may be directed fromthe second inventory 210 area to the first inventory 210 area. Inmulti-level facilities, lifts may be provided to convey bots 222 betweenlevels as necessary or desired. A bot 222 may be remotely directed, bythe control system 290, to go to a lift, get on the lift, get off thelift at the appropriate level, and proceed to an inventory 210 area onthe level. In at least some embodiments, as an alternative to directingthe movement of bots 222 between inventory 210 areas to meet demandneeds, control system 290 may instead direct picks from one inventory210 area to another inventory 210 area or areas. For example, if thecontrol system 290 detects that a particular inventory 210 area isfalling behind, the control system 290 may shift some of the pick loadto another inventory area 210.

In some implementations, an inventory 210 area may be subdivided intozones, for example a zone of the stock storage area corresponding to(and nearby) each induction station, and one or more bots may beassigned to operate within each zone. In these implementations, forexample to handle differences in demand, bots 222 may be directed,either automatically by control system 290 or by operator input to thecontrol system 290, from one zone to another zone in the inventory 210area, or alternatively pick load may be directed from one zone toanother zone in an inventory 210 area.

FIGS. 5A and 5B illustrate an example mobile robotic device (bot) thatmay be used in at least some embodiments. The shape, size, andconfiguration of the bot 222 and its components are examples forillustrative purposes, and are not intended to be limiting. FIG. 5Ashows a top view of the example bot 222, and FIG. 5B shows a side viewof the bot 222. A bot 222 may include at least a body or chassis, a liftmechanism located on top of the body for lifting storage units 220, andwheels (or other mechanisms such as tracks or treads) located underneaththe body. While FIG. 5A shows a circular lift mechanism, the liftmechanism may be other shapes. While FIGS. 5A and 5B show a bot 222 withfour wheels, a bot 222 may include more or fewer wheels, for example tworows of three wheels, three rows with four wheels in each row, and soon. Also, different wheels may have different functions; for example,one or more wheels may be drive wheels, one or more wheels may besteerable wheels, and one or more wheels may just be free-rollingwheels. In some implementations, a bot 222 may be configured to raiseand lower the body relative to the wheels. In some implementations, abot may not include a separate lift mechanism as shown in FIGS. 5A and5B for lifting storage units 220; instead, raising and lowering the bodyrelative to the wheels may act to lift and lower storage units 220.

A bot 222 may be short enough, with the lift mechanism lowered, to fitunder storage units 220. In some embodiments, the bot 322 may be shortenough to pass under other components of the materials handlingfacility, such as the conveyance mechanism 240 illustrated in FIG. 4. Asshown in FIG. 5B, a bot 222 may include at least one drive motor fordriving the wheels, at least one lift motor for raising and lowering thelift mechanism, communications and control components that maycommunicate (e.g., via wireless communications) with a control system290 or other external devices and control motions and actions of the bot222 under direction of the control system 290 and/or autonomously, andone or more sensors that may, for example sense the current location ofthe bot 222 in the materials handling facility and/or the location ofthe bot 222 relative to other external objects, devices, or stations inthe materials handling facility. Communications and control componentsmay include at least one computing device similar in architecture to theexample computer system 900 illustrated in FIG. 11, which may storecomputer code and data for controlling the bot 222. The sensors mayinclude optical sensors, tactile sensors, and/or other types of sensors.A bot 222 may also include at least one power supply and/or connectionfor connecting to an external power source. In some embodiments, thepower supply may be or may include a rechargeable battery. A bot 222 mayinclude other components, for example video cameras, audible alarms,external lights, access panels, external controls such as on/offbuttons, antennas, and Radio Frequency Identifier (RFID) devices. Forexample, a bot 222 may include an RFID tag that uniquely identifies thebot 222 in the materials handling facility. However, other techniques ordevices may be used to uniquely identify bots 222 in the materialshandling facility.

A materials handling facility may include sensors, RFID readers, orother devices that enable the control system 290 to determine, and trackthe location of specific bots 222 in the facility via wired or wirelesscommunications. A materials handling facility may also includetransmitters or similar devices that enable the control system 290 todirect the motions and actions of specific bots 222. In someimplementations, a materials handling facility may include guide strips,tracks, or other techniques for guiding the movements of the bots 222 inthe facility, either autonomously or under control of the control system290. For example, the aisles in the inventory 210 areas illustrated inFIGS. 3 and 4 may have guide strips embedded in or attached to thesurface of the floor for guiding the bots 222.

In some implementations, a materials handling facility may use two ormore different types or configurations of bots 222 for moving differenttypes or configurations of storage units.

FIGS. 6A and 6B illustrate an example storage unit that may be used inat least some embodiments. FIG. 6A shows a front view of an examplestorage unit 220, and FIG. 6B shows a side view of the example storageunit 220 of FIG. 6A. A storage unit 220 may include one or morelocations 226 into which units of items may be stowed. In someimplementations, only one type of item is stowed in each location 226.However, implementations are possible in which two or more differenttypes of items may be stowed in a location 226. FIG. 6A shows an exampleconfiguration for a storage unit 220 that may be used in someimplementations, and is not intended to be limiting. Storage units 220may have different configurations, and storage units 220 with differentconfigurations may be used together in an implementation of an inventory210 area. In various implementations, storage units 220 may havedifferent numbers of locations, and/or different sizes of locations. Insome implementations, a storage unit 220 may have two or more differentsizes of locations to accommodate more or fewer items and/or larger orsmaller items.

As shown in FIGS. 6A and 6B, a storage unit 220 may include legs thatraise the bottom shelf of the unit 220 high enough so that a bot 222 canfit under the unit 220. This example shows four legs arranged at thecorners of the unit 220; however, other numbers or configurations oflegs are possible.

Each storage unit 220 may include at least one indicator 228 associatedwith each location 226 of the storage unit 220. An indicator 228 may,for example, be used to indicate, at an induction station 212, that aunit of an item is to be removed from that location 226 and placed in aconveyance receptacle, under control of control system 290. As anotherexample, an indicator 228 may be used to indicate that a received itemor items are to be placed in an indicated location 226, under control ofcontrol system 290, at an induction station 212 or at some otherstation. The indicator 228 may be a light, an audio signal, or someother mechanism or combination of mechanisms capable of conveyingaudible, visual, and/or other information to a human operator. As analternative, or in addition, to indicators 228 physically locatedproximate to locations of storage unit 220, textual and/or graphicaldirections may be displayed on a monitor of a computer, hand-helddevice, etc., or printed to paper output for operator(s) at an inductionstation 212.

Each storage unit 220 may include at least one identifier 229, which maybe attached to or integrated in a leg (as shown) or attached to orintegrated in some other portion or surface of the unit 220. Theidentifier 229 may uniquely identify the unit 220 in an inventory 210area, or in the materials handling facility. For example, a storage unit220 may include an RFID tag that uniquely identifies the storage unit220 in the materials handling facility. However, other techniques ordevices may be used to uniquely identify storage units 220.

FIG. 7 illustrates an example bot with a storage unit, according to atleast some embodiments. A bot 222, under control of control system 290,may move underneath a storage unit 290, and may raise the lift mechanismto lift the storage unit 220 off the floor. The bot 222 may then, undercontrol of the control system and/or autonomously, move the storage unit220 to another location, for example to a specific induction station 212of an inventory 210 area. A bot 222 with a storage unit lifted, asillustrated in FIG. 7, may be referred to as a bot with storage unit224.

FIG. 8 illustrates an example physical layout of a materials handlingfacility, such as an order fulfillment facility or center, in whichembodiments of the robotic induction technique as described herein maybe implemented as part of a non-linear, unit-level materials handlingsystem. In an example conventional order fulfillment system, mixedbatches of items are picked from inventory and delivered directly to alinear automated sorting mechanism; the individual items are inductedonto fixed carriers or trays on the automated sorting mechanism. In theexample materials handling facility illustrated in FIG. 8, rather thanpicking mixed batches of items from inventory and delivering the pickedbatches of items directly to a linear automated sorting mechanism, in amaterials handling facility, such as an order fulfillment facility orcenter, in which an embodiment of the robotic induction technique isimplemented, one or more bots 322 move storage units 320 from stockstorage area(s) to induction station(s) 312 to fulfill portions or allof one or more requests or orders, under direction of control system390. At an induction station 312, an inductor pulls units of items fromlocations on storage units 320, under direction of control system 390.In this example physical materials handling facility, in the singulationand induction process, individual units of items are associated with andplaced into particular conveyance receptacles (e.g., totes or trays) ona conveyance mechanism 340 by the inductor, under direction of controlsystem 390 (induction). A single unit is placed in each conveyancereceptacle (singulation). Note that, in other implementations, toperform singulation and induction, the inductors remove single units ofitems from the storage units 320 and place the single units of itemsdirectly onto the conveyance mechanism 340. An inductor may be a humanagent of the materials handling facility, or may be an automatedmechanism controlled by control system 390.

FIG. 9 illustrates an example conveyance receptacle, according to atleast some embodiments. Receptacles, as used herein, may include, butare not limited to, any tote, basket, box, tray, or similar mechanismconfigured to receive individual units of items or batches of units ofitems in a materials handling facility. Conveyance receptacles 342 maycome in a variety of sizes, shapes, volumes, and configurations. In atleast some embodiments, conveyance receptacles 342 is not fixed to anyconveyance mechanism, and thus conveyance receptacles 342 can be removedfrom or added to a given conveyance mechanism. Each conveyancereceptacle 342 may be associated with or may include a unique conveyancereceptacle identifier 346 that uniquely identifies the particularconveyance receptacle 342 in the materials handling facility. Theconveyance receptacle identifier 346 may, for example, be indicated by abar code, Radio Frequency Identifier (RFID) device, or some otherscannable or readable mechanism, mark, or tag attached to or integratedwith the conveyance receptacle 342. FIG. 9 illustrates conveyancereceptacle 342 as including a receptacle identifier 346 attached to orintegrated with the conveyance receptacle 342 at two locations. However,conveyance receptacles 342 may have one, two, or more receptacleidentifiers 346 attached to or integrated with the receptacle 342.Receptacle identifiers 346 may be permanently fixed to conveyancereceptacles 342 or, alternatively, may be attachable/removable.

In at least some embodiments, each unit of each type of item handled bythe materials handling facility may include an item identifier. A typeof item may be referred to herein as simply an item. The term itemidentifier refers to a unique identifier associated with each particulartype of item handled by the materials handling facility. The term unitmay be used to refer to one (unit) of a type of item. Typically, but notnecessarily, each unit is tagged or otherwise marked with the itemidentifier. For example, units or collections of items in inventory maybe marked or tagged with a bar code, Universal Product Code (UPC),Stock-Keeping Unit (SKU) code, serial number, and/or other designation(including proprietary designations) that may be used as itemidentifiers to facilitate materials handling facility operations,including, but not limited to, stowing, rebinning, picking, sorting,packing and shipping. These designations, or codes, may identify itemsby type, and/or may identify individual items (units) within a type ofitem. Thus, in some implementations, each unit of item inducted into theconveyance mechanism includes a unit identifier that uniquely identifiesthe unit of item within the materials handling facility. In someimplementations, instead of inducting the units of items into conveyancereceptacles 342, which are inducted into the conveyance mechanism 340,the units of items are inducted directly into the conveyance mechanism340. The unique unit identifiers may then be used by the control systemto track and direct the singulated units of items in the materialshandling facility.

Cases, boxes, bundles, or other collections of units of items maysimilarly be marked or tagged with item identifiers. The units of itemsin a collection may all be of the same type of item, for example a caseof 12 units of a particular item, or may be a collection of one or moreunits of each of two or more heterogeneous items. A collection of unitsof item(s) (e.g., a case containing 12 units of an item, or a bundlecontaining one or more units of each of two or more heterogeneous items,such as a boxed or bundled set of three different books) may thus beconsidered or treated as a “unit” in the order fulfillment process. Adesignation, or code, may thus also identify a collection of units ofitem(s) as a “unit” in the order fulfillment process. Thus, embodiments,in addition to processing individual units of items, may also processcollections of units of item(s) designated as units. Therefore,collections of units of item(s) that are designated as units may besingulated and inducted into the conveyance mechanism at the inductionstations as well as individual units of items.

In at least some embodiments that employ conveyance receptacles 342 asshown in FIG. 8, a unit of an item may be associated with the particularconveyance receptacle 342 it is placed in. In at least some embodiments,the association of a unit of an item with a particular conveyancereceptacle 342 may be performed by reading, scanning or otherwiseentering an item identifier associated with the item and a conveyancereceptacle identifier 346 associated with the particular conveyancereceptacle 342 into which the unit is placed. The item identifier andreceptacle identifier 346 may be communicated to a control system 390 ofthe materials handling facility via wired and/or wirelesscommunications. In at least some embodiments in which singulated unitsof items are inducted directly onto the conveyance mechanism 340 insteadof into conveyance receptacles 342, the units of items may be associatedwith particular locations on the conveyance mechanism 340 into which theunits are inducted. For example, in some embodiments, the association ofa particular unit of an item with a particular location on conveyancemechanism 340 may be performed by reading, scanning or otherwiseentering a unique unit identifier associated with the unit of the itemand a location identifier associated with the location on the conveyancemechanism 340 into which the unit is placed. The unit identifier andlocation identifier may be communicated to a control system 390 of thematerials handling facility via wired and/or wireless communications.

Referring again to FIG. 8, a materials handling facility (in thisexample, order fulfillment center 300) may include a control system 390which may include, but is not limited to, one or more computer systems,one or more data storage devices, one or more wired and/or wirelessnetworks, control system software (programs, modules, drivers, userinterfaces, etc.), and one or more hand-held, mobile and/or fixedreaders, scanners or scanning devices that may be able to scan, receive,or otherwise detect the marks or tags (e.g., bar codes, radio frequencyidentification (RFID) tags, etc.) on individual items (units) orcollections of items (e.g., cases) and communicate with a controlstation or stations of the control system to, for example, determine andrecord the item and/or item type of the items. In addition, thehand-held, mobile and/or fixed readers, scanners or scanning devices mayalso be able to scan, receive, or otherwise detect the marks or tags(e.g., bar codes, radio frequency identification (RFID) tags, etc.)attached to or integrated with the conveyance receptacles 342. Thecontrol system 390 may also include one or more sensors, tracks, floorstrips, or other mechanisms or components that may be used to direct themovements of bots 322 in an inventory 310 area or elsewhere within thefacility. An example computer system that may be used in a controlsystem 390 is illustrated in FIG. 14.

At an induction station 312, a unit of an item picked from a storageunit 320 delivered to the station by a bot 322 under direction of thecontrol system 390 may be associated with a particular conveyancereceptacle 342 by reading, scanning, etc. the item identifier associatedwith the item and the conveyance receptacle identifier associated withthe conveyance receptacle 342 into the control system 390. This may beperformed manually (e.g., by an operator using a hand-held scanner), viaan automated scanning/reading process using fixed scanners/readers, orby a combination of manual and automatic scanning/reading. For example,an operator (inductor) at an induction station 312 may use a hand-heldscanner to scan a code off the unit of the item before or duringplacement of the unit into a “staged” conveyance receptacle 342, whilean automated reader may read (or may have already read) the conveyancereceptacle identifier from the conveyance receptacle 342 that is“staged” for the operator to place the unit of the item into.

Once a unit of an item is associated with and placed into a particularconveyance receptacle 342, the conveyance receptacle 342 may be inductedinto a conveyance mechanism 340 (e.g., a conveyor belt, roller system,or other conveyance mechanism) to be conveyed thereby to one or moredownstream processing stations for further processing of the unit of theitem. In various embodiments, the conveyance mechanism 340 may be aconveyance sorter mechanism that includes some method of divertingproduct off a conveyance path under control of control system 390.Examples of conveyance sorter mechanisms that may be used as conveyancemechanism 390 may include, but are not limited to, shoe sortermechanisms, pop up sorter mechanisms such as pop up wheel sortermechanisms, belt sorters, tray sorters, and so on. A pop up wheel sorterincludes powered wheels that rise up out of the conveyor to divertproduct off the conveyor onto a different path or to a location. Othertypes of conveyance sorter mechanism may be used in various embodiments.

A conveyance receptacle 342 may already be on the conveyance mechanism340 when the unit is associated with and placed into the receptacle 342.Alternatively, a conveyance receptacle 342 may be retrieved from aconveyance receptacle storage, stack, or other supply, the unit may beassociated with and placed into the receptacle 342, and the receptacle342 may then be inducted into or placed on the conveyance mechanism 340.In at least some embodiments, the conveyance receptacles 342 are notfixed to the conveyance mechanism 342; instead, the receptacles 342 areremovable bins, trays, totes, or similar devices. The conveyancemechanism 340 may be coupled to and controlled by the materials handlingfacility control system 390 via wired and/or wireless communications.The control system 390 may receive input from and send commands to theconveyance mechanism 340 to direct or control various operations of theconveyance mechanism 340.

The above describes embodiments of an induction station 312 in which ahuman operator performs at least a portion of the pulling of units ofitems from locations on storage units 320 automatically delivered to theinduction station 312 by bots under direction of control system 390,scanning/reading the units items and conveyance receptacles 342 toassociate single units of items to particular conveyance receptacles342, and placing the units into the conveyance receptacles 342. Inalternative embodiments, some or all of the activities described asbeing performed by a human operator may be performed by automatedmechanisms, which may be coupled to and under control of the materialshandling facility control system 390.

Once the conveyance receptacles 342B, each containing an individual unitof an item and each associated with the item it contains, are inductedinto the conveyance mechanism 340, the receptacles 342B may be conveyedor routed to any of one or more processing stations, to one or more ofvarious types of sorting mechanisms or processes, to other locations inthe materials handling facility, and so on. In at least someembodiments, the conveyance mechanism 340 may be directed by the controlsystem 390 as to the routing of each particular conveyance receptacle342B. Since each conveyance receptacle 342B is associated with theparticular item it contains, the control system 390 may, by tracking theconveyance receptacle 342B via its unique conveyance receptacleidentifier, route the particular item to an appropriate destination. Inimplementations in which the units of items are inducted directly intothe conveyance mechanism 340, the control system 390 may, for example,track and route the inducted individual units of items via their uniqueunit identifiers, or by some other method such as visual identificationof physical aspects of the units of items.

The control system 390 may also include or have access to information onthe orders in the order processing stream: for example, which orders arein the process of being fulfilled, which orders have been picked, whatitems in what quantities are included on each order, and so on. Byassociating particular items associated with particular conveyancereceptacles 342B via the conveyance receptacle identifiers with theorders being processed, the control system 390 may route conveyancereceptacles 342B containing units of items for particular orders toappropriate destinations for the orders, or for portions of the orders(e.g., to a particular one of one or more sorting stations 350 whereparticular orders are collected and grouped to be passed on to packingstations, or to other types of stations such as gift wrapping stationswhere pre-packing processing may be performed on orders or portions oforders, or even on individual units of items). The routing of conveyancereceptacles 342B and the particular items contained therein may beperformed automatically (e.g., by directing the conveyance mechanism 340to deliver a conveyance receptacle 342B to a particular destination)and/or by providing indications to human operators as to the routing orplacement of conveyance receptacles 342B and/or the items containedtherein. As an example of the former, a reader communicatively coupledto the control system 390 may automatically read the conveyancereceptacle identifier from a receptacle 342B as it passes on theconveyance mechanism 340, and the control system 390 may then direct theconveyance mechanism 340 to route the receptacle 342B on a particularone of two or more paths or branches of the conveyance mechanism 340,for example to a branch that conveys the receptacle 342B to a particularprocessing station such as sorting station 350A or 350B. As an exampleof the latter, once a receptacle 342B is routed to and arrives at aprocessing station such as a sorting station 350A, the conveyancereceptacle identifier may be manually or automatically scanned or readfrom the receptacle 342B, and the control system 390 may then activatean indicator on a particular slot, bin, shelf, etc. that is the correctdestination for the item contained in the receptacle 342B. The indicatormay be a light, an audio signal, or some other mechanism or combinationof mechanisms capable of conveying audio, visual, and/or otherinformation to a human operator. Alternatively, the indicator may betextual or graphical directions displayed on a monitor of a computer,hand-held device, etc., or printed to paper output.

Once the unit of an item has been pulled from its associated conveyancereceptacle 342B at whatever destination the receptacle is routed to(e.g., a sorting station 350), the item and receptacle 342B may bedisassociated by the control system 390. The empty (and unassociated)conveyance receptacle 340A may then be re-inducted, if necessary, intothe conveyance mechanism 340 to be returned, e.g. to an inductionstation 312 (there may be more than one induction station 312;therefore, a receptacle 342A is not necessarily returned to the sameinduction station 312 it came from). However, an empty conveyancereceptacle 342A is not necessarily immediately re-inducted into theconveyance mechanism 340 when emptied. The conveyance receptacles 342are not fixed or attached to the conveyance mechanism 340, and there isno necessary ordering of the receptacles 342 on the conveyance mechanism340; therefore, an emptied conveyance receptacle 342A may be removed andset aside if necessary or desired. When an empty conveyance receptacle342A arrives at an induction station 312 by the return path of theconveyance mechanism 340, the conveyance receptacle 342A may beassociated with and used to contain and convey a selected unit of anitem from a storage unit 320 currently at the particular inductionstation 312, or alternatively may be set aside into a conveyancereceptacle storage area or stack if necessary or desired. Again, theconveyance receptacles 342 are not fixed to the conveyance mechanism340, and are not ordered on the conveyance mechanism 340. In otherwords, the conveyance mechanism 340, and thus the entire materialshandling system, is non-linear.

The above describes a non-linear, unit-level materials handling systemfor sorting units of items for delivery to various destinationsaccording to requests or orders and in which the items are pickedaccording to a singulating and inducting, robot-assisted pickingprocess. In the picking process, in a given inventory 310 area, bots 322deliver storage units 320 from stock storage, each containing one ormore types of items at one or more locations, to one or more inductionstations 100 under direction of control system 390. At the inductionstations 312, individual units of items are pulled from locations on thestorage units 320, associated with particular conveyance receptacles342, and placed into the receptacles 342, with one and only one unit perreceptacle 342. The conveyance receptacles with items 342B are inductedinto a conveyance mechanism 340 under the direction of control system390 that, through various mechanisms, directs the receptacles 342B, eachcontaining and associated with a single unit of an item, to particulardestinations. One such destination, in some embodiments, is a sortingstation 350, where the individual items may be manually or automaticallyretrieved from conveyance receptacles 342B and manually or automaticallyplaced into slots or bins corresponding to particular orders. An examplesorting station 350 is illustrated in FIG. 11. Empty conveyancereceptacles 342A may be returned from the destinations to the one ormore induction stations 312.

As noted above, the conveyance mechanism 340 is non-linear. Theconveyance receptacles 342 are not fixed to the conveyance mechanism340, and are not ordered on the conveyance mechanism 340. The conveyancemechanism 340 includes at least one conveyance path from the inductionstation(s) 312 in inventory area(s) 310 to one or more destinations toconvey conveyance receptacles 342B each containing a single unit to theone or more destinations under direction of the control system 390. Theconveyance mechanism 340 also includes at least one return path from atleast one of the destinations to return empty conveyance receptacles342A to the induction station(s) 312. Additional empty conveyancereceptacles 342A may be inducted into the conveyance mechanism 340, forexample to increase capacity of the non-linear, unit-level materialshandling system. Empty conveyance receptacles 342A may be removed fromthe conveyance mechanism 340, for example to reduce capacity of thenon-linear, unit-level materials handling system.

Thus, using the non-linear, unit-level materials handling system asdescribed herein, conveyance receptacles 342 may be added to or removedfrom the conveyance mechanism 340 as necessary or desired, for exampleto dynamically adjust to changes in throughput. This may allowembodiments to achieve greater velocity and total throughput than, forexample, fixed, linear tilt-tray sorting mechanisms, which have a fixednumber of carriers that go around in a fixed, non-flexible loop.Further, the conveyance receptacles 340 may handle a wider variety ofsizes and types of items than for example a fixed, linear tilt-traysorting mechanism, with no lower limit on the size of items that can beplaced in a receptacle 342, and the upper limit being thevolume/dimensions of the receptacles 342 themselves. Further, differentsizes of receptacles 342 may be inducted into the conveyance mechanism340 as necessary or desired. Larger receptacles 342 may be used if thereare a large number of bigger items being processed in the materialshandling facility. Smaller receptacles 342 may be used if the materialshandling facility handles mostly small items, which would allow thetotal number of receptacles 342 on the conveyance mechanism 340 at onetime to be increased. The maximum number of receptacles 342 that can beon the conveyance mechanism 340 at one time is limited by the size ofthe receptacles 342; therefore, the use of smaller receptacles may allowmore receptacles 342 to be on the conveyance mechanism 340 at one time.Further, a mix of different sizes and configurations of receptacles 342may be used on the conveyance mechanism 340 at one time, unlike linear,fixed-receptacle sorting mechanisms that typically have one fixed sizeand configuration of carrier (e.g., tilt tray), which is fixed to thesorting mechanism. Further, if the requirements of the materialshandling facility change, for example if the materials handling facilityincreases or decreases the average size of items carried in inventory,the non-linear, unit-level materials handling system may be adapted tohandle the change simply, quickly and inexpensively by replacing some orall of the conveyance receptacles 342 and possibly making some otherrelatively inexpensive modifications, with little or no down time,rather than replacing or modifying entire linear, fixed-receptaclesorting mechanisms, which can be a very expensive and time-consumingprocess, and which might require significant down time.

As previously noted, in some implementations, rather than associatingunits of items with conveyance receptacles 342 and placing the units ofitems into the conveyance receptacles 342 as described for FIG. 8, theunits of items may be directly inducted into the conveyance mechanism340. In these implementations, the control system 390 may track androute the inducted individual units of items, for example via uniqueunit identifiers associated with the units or by some other method.

FIG. 10 illustrates operation of an example induction station accordingto at least some embodiments. Requests (e.g., orders) for items fromrequestors may be received at the materials handling facility. Tofulfill the requests, a control system 390 may direct bots 322 in one ormore inventory areas to retrieve storage units 320 that contain one ormore of the requested items and to deliver the storage units 320 toparticular induction stations 312. At an induction station 312, aninductor (which may be either a human agent or an automated device),under direction of control system 390, inducts individual units of items308 into the conveyance mechanism 340. For example in implementationsthat employ conveyance receptacles 340, the inductor picks units 308 ofone or more types of items from locations on the storage unit 320 andplaces each unit 308 of items into a pick receptacle 342. The unit 308may be associated with a particular conveyance receptacle 342 and placedinto the receptacle 342 (induction). One and only one unit 308 may beassociated with and placed into each conveyance receptacle 342(singulation). Alternatively, in some implementations, the units 308 maybe directly inducted into the conveyance mechanism 340, as previouslydescribed.

Control system 390 may provide audible, visual, or other indications tohuman operators as to the selection of units 308 of items from storageunits 320 and placing of the items into conveyance receptacles 342. Forexample, once a particular storage unit 320 arrives at an inductionstation 312, the control system 390 may be manually or automaticallynotified. The control system 390 may activate an indicator 328associated with a particular location of the storage unit 320 toindicate that a unit 308 is to be removed from that location and placedin a next receptacle 342. The indicator 328 may be a light, an audiosignal, or some other mechanism or combination of mechanisms capable ofconveying audible, visual, and/or other information to a human operator.As an alternative, or in addition, to indicators 328 physically locatedproximate to locations of storage unit 320, textual and/or graphicaldirections may be displayed on a monitor of a computer, hand-helddevice, etc., or printed to paper output for operator(s) at inductionstation 312. After the unit 308 is associated with and placed inreceptacle 342, the control system 390 may activate another indicator328 on the storage unit 320 to indicate another location from whichanother unit of an item is to be pulled, or may direct the bot 322 toreturn the storage unit 320 to stock storage (or to take the storageunit 320 to another station), and may direct another bot 322 (or thesame bot 322) to bring a next storage unit 320 to the induction station312.

In at least some embodiments that employ conveyance receptacles 342, theassociation of a unit of an item 308 with a particular conveyancereceptacle 342 may be performed by reading, scanning or otherwiseentering an item identifier associated with the item and a uniqueconveyance receptacle identifier 346 associated with the particularconveyance receptacle 342 into which the unit 308 is placed. In at leastsome embodiments, a fixed, mobile, or hand-held reader 394 may be usedto read or scan the item identifier and receptacle identifier 306.Associating a unit 308 of an item with a particular conveyancereceptacle 304 may be performed manually (e.g., by a human operatorusing a hand-held scanner), via an automated scanning/reading processusing fixed scanners/readers, or by a combination of manual andautomatic scanning/reading. For example, an operator at the inductionstation 312 may use a hand-held scanner 394 to scan a code off the unitof the item 308 before or during placement of the unit 308 into a“staged” conveyance receptacle 342, while an automated reader may read(or may have already read) the conveyance receptacle identifier from theconveyance receptacle 342 that is “staged” for the operator to place theunit of the item into. The read or scanned item identifier andreceptacle identifier 346 may be communicated to a control system 390 ofthe materials handling facility via wired and/or wirelesscommunications. In at least some embodiments in which singulated unitsof items are inducted directly onto the conveyance mechanism 340 insteadof into conveyance receptacles 342, the units of items may instead beassociated with particular locations on the conveyance mechanism 340into which the units are inducted.

In at least some embodiments that employ conveyance receptacles 342,once a unit of an item 308 is associated with and placed into aparticular conveyance receptacle 342, the conveyance receptacle 342 maybe inducted into conveyance mechanism 340 (e.g., a conveyor belt, rollersystem, or other conveyance mechanism) to be conveyed thereby to one ormore downstream processing stations, for example sorting stations, forfurther processing of the unit of the item 308. For example, conveyancemechanism 340 may convey receptacles 342 containing units of items 308to one or more sorting stations as illustrated in FIG. 11. Conveyancemechanism 340 may also return empty receptacles 342 from the downstreamprocessing station(s). In at least some embodiments, the conveyancemechanism 340 may be a conveyance sorter mechanism that includes somemethod of diverting product off a conveyance path under control ofcontrol system 390. Examples of conveyance sorter mechanisms that may beused as conveyance mechanism 340 may include, but are not limited to,shoe sorter mechanisms, pop up sorter mechanisms such as pop up wheelsorter mechanisms, belt sorters, tray sorters, and so on. However, othermechanisms may be used as a conveyance mechanism 340.

In at least some embodiments that employ conveyance receptacles 342, theconveyance receptacle 342 may already be on the conveyance mechanism 340when the unit 308 is associated with and placed into the receptacle 342.Alternatively, a conveyance receptacle 342 may be retrieved from aconveyance receptacle storage, stack, or other supply 314, a unit 308may be associated with and placed into the receptacle 342, and thereceptacle 342 may then be inducted into or placed on the conveyancemechanism 340. Once the conveyance receptacles 342, each containing anindividual unit 308 of an item and each associated with the item itcontains, are inducted into conveyance mechanism 340 at inductionstation 312, the receptacles 342 may be conveyed to any of one or moredownstream processing stations, to one or more of various types ofsorting mechanisms, to other locations in the materials handlingfacility, and so on. For example, conveyance receptacles 342 may beconveyed to a sorting station 350 as illustrated in FIG. 11.

The conveyance mechanism 340 may be coupled to and controlled by thematerials handling facility control system 390 via wired and/or wirelesscommunications. The control system 390 may receive input from and sendcommands to the conveyance mechanism 340 to direct or control variousoperations of the conveyance mechanism 340. The control system 390 may,for example, control conveyance mechanism 340 to direct a particularconveyance receptacle 342 and its associated unit 308 to a particularsorting station 350, as illustrated in FIG. 8. In implementations inwhich the units of items are inducted directly into the conveyancemechanism 340, the control system 390 may instead track and route theinducted individual units of items 308 via unique unit identifiersassociated with the units 308, or by some other method such as visualidentification of physical aspects of the units of items 308.

In some embodiments, a human operator may perform at least a portion ofthe operations at induction station 312 under direction of controlsystem 390. In alternative embodiments, some or all of the operationsmay be performed by automated mechanisms, which may be coupled to andunder control of control system 390.

In at least some embodiments that employ conveyance receptacles 342,empty conveyance receptacles 342 may be returned to induction station312 from one or more locations in the materials handling facility (e.g.,from one or more sorting stations 350) on conveyance mechanism 340. Asupply 314 of conveyance receptacles 342 may be kept at or nearinduction station 312. Arriving receptacles 342 may remain on conveyancemechanism 312 to be used to receive, contain and convey units 308 ofitems or, alternatively, may be removed and placed into supply 314.

FIG. 11 illustrates operation of an example sorting station that may beused in embodiments of a non-linear, unit-level materials handlingsystem. In at least some embodiments that employ conveyance receptacles342, once the conveyance receptacles 342, each containing an individualunit 308 of an item and each associated with the item it contains, areinducted into the conveyance mechanism 340, for example at an inductionstation 312 as illustrated in FIG. 10, at least some of the receptacles342 may be conveyed to sorting station 350. In at least someembodiments, the conveyance mechanism 340 may be directed by the controlsystem 390 as to the disposition of each particular conveyancereceptacle 342. Since each conveyance receptacle 342 is associated withthe particular item it contains, the control system 390 may, by trackinga particular conveyance receptacle 342 via its unique conveyancereceptacle identifier, direct the conveyance mechanism 340 to route theparticular conveyance receptacle 342 and its associated unit of an item308 to sorting station 350 from an originating induction station 312. Inimplementations in which the units of items are inducted directly intothe conveyance mechanism 340, the control system 390 may instead trackand route the inducted individual units of items 308 via unique unitidentifiers associated with the units 308, or by some other method suchas visual identification of physical aspects of the units of items 308.

To route a particular conveyance receptacle 342 or a unit 308 of an itemto a particular destination, the control system 390 may also include orhave access to information on the orders in the order processing stream:which orders are in the process of being fulfilled, which items forwhich orders have been picked and inducted at induction station(s) 312,what items in what quantities are included on each order, and so on. Inat least some embodiments that employ conveyance receptacles 342, thecontrol system 390 may associate a particular conveyance receptacle 342including a unit 308 of a particular item with a particular ordercurrently being processed in the order fulfillment process, and mayroute the conveyance receptacle 342 to an appropriate destination forthe order (e.g., to sorting station 350 of FIG. 11). The routing ofconveyance receptacles 342 may be performed automatically (e.g., bycontrol system 390 directing the conveyance mechanism 340 to deliver aconveyance receptacle 342 to a particular destination). As an example, areader communicatively coupled to the control system 390 mayautomatically read the conveyance receptacle identifier from areceptacle 342 as it passes the reader on the conveyance mechanism 340,and the control system 390 may then direct the conveyance mechanism 340to route the receptacle 342 on a particular one of two or more paths orbranches of the conveyance mechanism 340, for example to a path thatconveys the receptacle 342 to sorting station 350. In implementations inwhich the units of items are inducted directly into the conveyancemechanism 340, the control system 390 may instead track and route theinducted individual units of items 308 via unique unit identifiersassociated with the units 308, or by some other method such as visualidentification of physical aspects of the units of items 308.

Control system 390 may also provide audible, visual, or otherindications to human operators as to the routing or placement ofconveyance receptacles 342 and/or the units 308 of items. For example,in at least some embodiments that employ conveyance receptacles 342,once a particular conveyance receptacle 342 arrives at sorting station350, the conveyance receptacle identifier may be manually orautomatically scanned or read from the receptacle 342 and communicatedto control system 390. In at least some embodiments in which units ofitems 308 are inducted directly into the conveyance mechanism 340, oncea particular unit 308 arrives at sorting station 350, the unique unitidentifier of the unit 308 may be manually or automatically scanned orread from the unit 308 and communicated to control system 390. In atleast some embodiments, a fixed, mobile, or hand-held reader 396 may beused to read or scan the conveyance receptacle identifier and/or theunit identifiers of units of items 308. After the conveyance receptacleidentifier 306 or the unit identifier of the unit 308 is read, thecontrol system 390 may activate an indicator 358 associated with aparticular order slot 356 of an order sorting bin 354 located at thesorting station 350 that is assigned to an order that is associated withthe unit 308 of the item. The indicator 358 may be a light, an audiosignal, or some other mechanism or combination of mechanisms capable ofconveying audible, visual, and/or other information to a human operator.As an alternative, or in addition, to indicators 358 physically locatedproximate to slots 356 on sorting bin 354, textual and/or graphical itemplacement directions may be displayed on a monitor of a computer,hand-held device, etc., or printed to paper output for operator(s) atsorting station 352.

There may be one or more order processing stations 360 associated withsorting station 352. In this example, an order processing station 360 islocated on the other side of order sorting bin 354. An order processingstation 360 may, for example, be a packing station at which one or moreunits 308 of items for an order are processed, packed, and labeled forshipping to the customer. The order slots 356 may be pass-through slotsinto one side of which units 308 of items may be placed by sorting 350,and out of which individual or collections of units 308 of items may beremoved for processing by order processing 360. FIG. 11 shows an examplesingle order sorting bin 354 at sorting station 350. However, there maybe more than one order sorting bin 354 at a sorting station 350. Forexample, in some implementations there may be two order sorting bins354, with one bin located on each side of sorting station 350, and witha separate order processing station 360 located on the opposite side ofeach bin 354.

FIG. 11 shows an example configuration for an order sorting bin 354 thatmay be used in some implementations, and is not intended to be limiting.Sorting bins 354 may have different configurations, and sorting bins 354with different configurations may be used together in an implementationof a sorting station 350. In various implementations, sorting bins 354may have different numbers of slots, and/or different sizes of slots. Asexamples, an order sorting bin 354 may have 112 6″×6″ slots, or 3212″×12″ slots, or 24 12″×18″ slots, or 24 16″×16″ slots. A “hybrid”sorting bin 354 may have two or more different sizes of slots toaccommodate larger or smaller orders and/or larger or smaller items; asan example, a hybrid order sorting bin 354 may include six 16″×16″slots, eight 12″×18″ slots, eight 12″×12″ slots, and 22 9″×9″ slots.Note that these examples are not intended to be limiting.

In at least some embodiments, units 308 of items may be removed fromconveyance mechanism 340 and placed into a particular slot 356 of anorder sorting bin 354 as indicated by the control system 390, forexample by the control system 390 activating an indicator 358 associatedwith the slot 356 into which the unit 308 is to be placed to indicate tothe operator that the unit 308 from the current receptacle 342 is to beplaced into that slot 356. For example, in FIG. 11, item 308 isillustrated as being placed into slot (row 3, column 2) of order sortingbin 354 as directed by control system 390 activating the indicator 358for that slot 356. Sorting bin 354 may also include indicatorsassociated with the slots 356 on the order processing station 360 sidewhich control system 390 may activate to indicate to operators at theorder processing station 360 that a particular slot 356 is ready to beprocessed (e.g., that all units 308 of all items for an order have beenplaced into that slot). In this example, control system 390 hasindicated to operator(s) at order processing station 360 that an order160 in slot (row 2, column 3) has been completed. An operator may thenpull the order 362 from the indicated slot 356 for further processing.

In at least some implementations, a materials handling process using acontrol system 390, induction stations 312, sorting stations 350, and aconveyance mechanism 340 as described herein may free operators atsorting stations 350 from having to scan each individual item 308 duringsorting. In at least some embodiments, the conveyance receptacleidentifiers or unit identifiers of units 308 may be automatically readby a reader 396 as the receptacles 342 or units 308 approach or enterthe location of sorting station 350 at which the operator removes units308 from receptacles 342. The operator may thus simply remove a unit 308from a receptacle 342 or directly from the conveyance mechanism 340,look to see which slot indicator 356 in a bin 354 is currently activatedby control system 390, and place the unit 308 into the indicated slot354.

In at least some embodiments that employ conveyance receptacles 342,once a unit 308 of an item has been pulled from its associatedconveyance receptacle 342 at sorting station 350, the item 308 andreceptacle 342 may be disassociated in the control system 390. Thecontrol system 390 may determine via the processing at sorting station350, or alternatively may be informed via operator interaction with thecontrol system 390, that the conveyance receptacle 342 is now empty. Theempty (and unassociated) conveyance receptacle 342 may then bere-inducted, if necessary or desired, into the conveyance mechanism 340to be returned, for example, to a induction station 312. There may bemore than one induction station 312 in a materials handling facility;therefore, a receptacle 342 is not necessarily returned to the sameinduction station 312 that it originated from. However, a conveyancereceptacle 342 is not necessarily immediately re-inducted into theconveyance mechanism 342 when emptied. The conveyance receptacles 342are not fixed or attached to the conveyance mechanism 340, and there isno necessary ordering of the receptacles 342 on the conveyance mechanism340; therefore, an emptied conveyance receptacle 342 may be removed andset aside if necessary or desired.

FIG. 12 is a flowchart illustrating a method for robotic induction in amaterials handling facility, according to at least some embodiments. Asindicated at 400, a robotic device (bot) may be directed, for example bya control system of the materials handling facility, to deliver aparticular storage unit from a stock storage area to a particularinduction station in an inventory area. Example inventory areas withstock storage areas and induction stations are shown in FIGS. 3, 4, and8. An example bot is shown in FIGS. 5A and 5B, an example storage unitis shown in FIGS. 6A and 6B, and an example bot with storage unit isshown in FIG. 7. An example induction station is shown in FIG. 10. Anexample computer system that may implement software components andfunctionality of the control system is illustrated in FIG. 14.

As indicated at 402, at the induction station, a unit of an item may beselected from an indicated location in the storage unit, under directionof the control system. As indicated at 404, the unit of the item may beinducted into a conveyance mechanism, under direction of the controlsystem. In at least some embodiments that employ conveyance receptacles,an item identifier of the selected unit may be associated with areceptacle identifier of an empty conveyance receptacle. An exampleconveyance receptacle is illustrated in FIG. 9. The selected unit may beplaced into the associated conveyance receptacle, and, the conveyancereceptacle containing the unit may be inducted into the conveyancemechanism. Alternatively, the unit of the item may be inducted directlyinto the conveyance mechanism. As indicated at 406, the conveyancemechanism may convey the unit of the item to a downstream processingstation, in at least some embodiments under direction of the controlsystem to a particular one of two or more downstream processingstations. In some embodiments, the downstream processing station towhich the unit of the item is directed may be one of one or more sortingstations as illustrated in FIG. 11.

At 408, if there are more items to be picked from this storage unit, themethod may return to element 402 to process a next unit of an item. Notethat the storage unit may store units of different types of items atdifferent locations, and the next item picked from the storage unit maybe another unit of the same type of item or a unit of a different typeof item. Also note that the units of items picked from a storage unitmay be for one order or for two or more different orders.

At 408, if there are not more items to be picked from this storage unit,the bot may be directed to return the storage unit to the stock storagearea, or alternatively to another induction station, as indicated at410. Another bot, or the same bot, may then be directed by the controlsystem to deliver another storage unit to the induction station, asindicated by the return arrow from 410 to 400.

Note that there may be more than one induction station in an inventoryarea, and therefore the method as illustrated in FIG. 12 may beperformed at each induction station. In addition, there may be more thanone inventory area in a materials handling facility, and the method asillustrated in FIG. 12 may be performed in two or more of the inventoryareas. At any one time in a given inventory area, different bots may bedelivering different storage units to different induction stations,and/or returning storage units to stock storage or moving storage unitsfrom one induction station to another. In addition, while FIG. 12indicates that a bot is not directed to deliver a storage unit to agiven induction station until after a first bot has been directed tomove a storage unit from the induction station, in at least someembodiments, one or more other bots may be directed to move storageunits to a particular induction station while a storage unit is beingprocessed at the station as indicated at 402 through 408 of FIG. 12. Inat least some embodiments, a bot may hold a storage unit in a stagingarea while waiting for processing of the storage unit at the inductionstation to be completed and for the storage unit to be moved by itsassociated bot.

While not shown, in some implementations, received stock may be placedinto a storage unit while the storage unit is at an induction station.In at least some embodiments, units or collections of one or more typesof items received by a receiving process of the materials handlingfacility may be delivered to an induction station, and may be placedinto one or more locations of the storage unit while it is at thestation, under direction of the control system. Alternatively, aninventory area may have at least one stowing station to which botsdeliver storage units for stowing of items to locations in the storageunits under direction of the control system. The stowing process may besimilar to the picking method shown in FIG. 12, but with units (orcollections) being stowed to indicated locations, rather than pickedfrom indicated locations.

Note that one or more of the elements of FIG. 12 may be performed by ahuman operator under direction of the materials handling facilitycontrol system, or alternatively may be performed by one or moreautomated mechanisms which may be coupled to (wirelessly or wired) andunder control of the materials handling facility control system.

FIG. 13 is a flowchart illustrating a method of operation in anon-linear, unit-level materials handling system in which an embodimentof the robotic induction technique is implemented, according to at leastsome embodiments. This flowchart illustrates how the various componentsdescribed herein, e.g. one or more induction stations, a conveyancemechanism, one or more sorting stations, and a control system, may beintegrated to form a non-linear, unit-level materials handling systemfor handling the sortation of items to fulfill orders in the materialshandling facility. The method as illustrated in FIG. 13 may be performedas a continuous or near-continuous process by the non-linear, unit-levelmaterials handling system in the materials handling facility to sort acontinuous or near-continuous incoming stream of heterogeneous itemspicked to fulfill orders into their respective orders.

Element 500 may be performed according to the method as illustrate inFIG. 12. Element 502 may be performed by a conveyance mechanism, such asconveyance mechanism illustrated in FIGS. 3, 4 and 8, which may becontrolled by the control system. Elements 504 through 510 may beperformed at a sorting station, such as the sorting station 152illustrated in FIG. 11, under direction of the control system. Anexample computer system that may implement software components andfunctionality of the control system is illustrated in FIG. 14.

As indicated at 500, at one or more induction stations in one or moreinventory areas, a control system may direct the singulation of units ofitems from storage units delivered by bots to the induction stations,and the induction of the units of items into a conveyance mechanism. Inat least some embodiments that employ conveyance receptacles,singulation and induction may involve placing of the single units ofitems into conveyance receptacles on a conveyance mechanism. In asingulating induction process as illustrated in FIG. 13, at an inductionstation, individual units of items are removed from one or morelocations on a given storage unit delivered to the induction station bya robotic device; the individual units may be placed into and associatedwith particular conveyance receptacles of a conveyance mechanism, oralternatively the individual units of items may be inducted directlyinto the conveyance mechanism.

As indicated at 502, the conveyance mechanism may convey the inductedunits of items from the one or more induction stations of the one ormore inventory areas to particular ones of one or more sorting stationsin the materials handling facility. A particular unit of an item may beconveyed to a sorting station that is the destination for an order thatspecifies at least one unit of the item. A control system may direct theconveyance mechanism to route a particular unit of an item to thecorrect destination, e.g. to a sorting station at which an orderspecifying at least one unit of the item is to be collected forprocessing.

As indicated at 504, the inducted units of particular items may bereceived at a sorting station. At the sorting station, the units ofparticular items may be manually or automatically removed from theconveyance mechanism, as indicated at 506. In at least some embodimentsthat employ conveyance receptacles, the units of particular items may bemanually or automatically removed from the conveyance receptacles. Eachunit may then be manually or automatically placed into a particularlocation at the sorting station associated with an order that indicatesat least one unit of the particular item, as indicated at 508. In atleast some embodiments, the particular location may be a particular slotof an order sorting bin, such as the example order sorting binillustrated in FIG. 11.

In at least some embodiments that employ conveyance receptacles, toplace a unit into a particular location at the sorting station, therespective receptacle identifier may be manually or automatically readfrom the conveyance receptacle at or near the sorting station, and anindicator associated with the particular location may be automaticallyactivated in response to reading the receptacle identifier to indicateto an operator that the unit of the particular item associated with theconveyance receptacle is to be placed into that particular location. Inat least some embodiments in which units of items are inducted directlyinto the conveyance mechanism, to place a unit into a particularlocation at the sorting station, the respective unit identifier of theunit of the item may be manually or automatically read from the unit ator near the sorting station, and an indicator associated with theparticular location may be automatically activated in response toreading the unit identifier to indicate to an operator that the unit ofthe particular item associated with the conveyance receptacle is to beplaced into that particular location

In at least some embodiments that employ conveyance receptacles, theempty conveyance receptacles may be, but are not necessarily inductedinto a return path of the conveyance mechanism to return the conveyancereceptacles to the induction station(s). The control system may directthe conveyance mechanism to return the empty conveyance receptacles toparticular ones of the one or more induction stations, or alternativelymay direct the conveyance system to route empty conveyance receptaclesto some other destination. At an induction station, a returned emptyconveyance receptacle may be associated with another item, receive aunit of the item selected from a storage unit at the station, and maythen be conveyed by the conveyance mechanism to a sorting station underdirection of the control system. Alternatively, empty conveyancereceptacles may be removed from the conveyance mechanism at the sortingstation(s), induction station(s), or at other locations along ordestinations of the conveyance mechanism.

Illustrative System

In at least some embodiments, a system that implements one or morecomponents of a robotic induction technique and/or of a non-linear,unit-level materials handling system that implements the roboticinduction technique as described herein may include a general-purposecomputer system that includes or is configured to access one or morecomputer-accessible media, such as computer system 900 illustrated inFIG. 14. In the illustrated embodiment, computer system 900 includes oneor more processors 910 coupled to a system memory 920 via aninput/output (I/O) interface 930. Computer system 900 further includes anetwork interface 940 coupled to I/O interface 930.

In various embodiments, computer system 900 may be a uniprocessor systemincluding one processor 910, or a multiprocessor system includingseveral processors 910 (e.g., two, four, eight, or another suitablenumber). Processors 910 may be any suitable processors capable ofexecuting instructions. For example, in various embodiments, processors910 may be general-purpose or embedded processors implementing any of avariety of instruction set architectures (ISAs), such as the x86,PowerPC, SPARC, or MIPS ISAs, or any other suitable ISA. Inmultiprocessor systems, each of processors 910 may commonly, but notnecessarily, implement the same ISA.

System memory 920 may be configured to store instructions and dataaccessible by processor(s) 910. In various embodiments, system memory920 may be implemented using any suitable memory technology, such asstatic random access memory (SRAM), synchronous dynamic RAM (SDRAM),nonvolatile/Flash-type memory, or any other type of memory. In theillustrated embodiment, program instructions and data implementingdesired functions, such as those methods and techniques described abovefor a control system in a robotic induction technique and/or in anon-linear, unit-level materials handling system that implements therobotic induction technique, are shown stored within system memory 920as code 925 and data 926.

In at least some embodiments, I/O interface 930 may be configured tocoordinate I/O traffic between processor 910, system memory 920, and anyperipheral devices in the device, including network interface 940 orother peripheral interfaces. In some embodiments, I/O interface 930 mayperform any necessary protocol, timing or other data transformations toconvert data signals from one component (e.g., system memory 920) into aformat suitable for use by another component (e.g., processor 910). Insome embodiments, I/O interface 930 may include support for devicesattached through various types of peripheral buses, such as a variant ofthe Peripheral Component Interconnect (PCI) bus standard or theUniversal Serial Bus (USB) standard, for example. In some embodiments,the function of I/O interface 930 may be split into two or more separatecomponents, such as a north bridge and a south bridge, for example.Also, in some embodiments some or all of the functionality of I/Ointerface 930, such as an interface to system memory 920, may beincorporated directly into processor 910.

Network interface 940 may be configured to allow data to be exchangedbetween computer system 900 and other devices attached to a network 800,such as other computer systems, communications devices, controlmechanisms, readers, scanners and so on that are components of a roboticinduction technique and/or of a non-linear, unit-level materialshandling system that implements the robotic induction technique. Thecommunications channels may include, but are not limited to conventionaland mobile telephone and text messaging communications channels. Networkinterface 940 may commonly support one or more wireless networkingprotocols (e.g., Wi-Fi/IEEE 802.11, or another wireless networkingstandard). However, in various embodiments, network interface 940 maysupport communication via any suitable wired or wireless general datanetworks, such as other types of Ethernet network, for example.Additionally, network interface 940 may support communication viatelecommunications/telephony networks such as analog voice networks ordigital fiber communications networks, via storage area networks such asFibre Channel SANs, or via any other suitable type of network and/orprotocol.

In some embodiments, system memory 920 may be one embodiment of acomputer-accessible medium configured to store program instructions anddata as described above for FIGS. 1 through 12 for implementing acontrol system for, or possibly other components of, a robotic inductiontechnique and/or of a non-linear, unit-level materials handling systemthat implements the robotic induction technique. However, in otherembodiments, program instructions and/or data may be received, sent orstored upon different types of computer-accessible media. Generallyspeaking, a computer-accessible medium may include storage media ormemory media such as magnetic or optical media, e.g., disk or DVD/CDcoupled to computer system 900 via I/O interface 930. Acomputer-accessible medium may also include any volatile or non-volatilemedia such as RAM (e.g. SDRAM, DDR SDRAM, RDRAM, SRAM, etc.), ROM, etc,that may be included in some embodiments of computer system 900 assystem memory 920 or another type of memory. Further, acomputer-accessible medium may include transmission media or signalssuch as electrical, electromagnetic, or digital signals, conveyed via acommunication medium such as a network and/or a wireless link, such asmay be implemented via network interface 940.

Various embodiments may further include receiving, sending or storinginstructions and/or data implemented in accordance with the foregoingdescription upon a computer-accessible medium. Generally speaking, acomputer-accessible medium may include storage media or memory mediasuch as magnetic or optical media, e.g., disk or DVD/CD-ROM, volatile ornon-volatile media such as RAM (e.g. SDRAM, DDR, RDRAM, SRAM, etc.),ROM, etc., as well as transmission media or signals such as electrical,electromagnetic, or digital signals, conveyed via a communication mediumsuch as network and/or a wireless link.

The various methods as illustrated in the Figures and described hereinrepresent exemplary embodiments of methods. The methods may beimplemented in software, hardware, or a combination thereof. The orderof method may be changed, and various elements may be added, reordered,combined, omitted, modified, etc.

Various modifications and changes may be made as would be obvious to aperson skilled in the art having the benefit of this disclosure. It isintended that the invention embrace all such modifications and changesand, accordingly, the above description to be regarded in anillustrative rather than a restrictive sense.

What is claimed is:
 1. A unit-level materials handling facility,comprising: an inventory area comprising a plurality of portable storageunits, wherein each portable storage unit of the plurality of portablestorage units comprises one or more locations for stowing a firstplurality of types of items, wherein the inventory area furthercomprises one or more induction stations, each induction station locatedproximate to a portion of a conveyance mechanism, and wherein theinventory area includes one or more mobile robotic devices operable totransport the portable storage units within the inventory area; aseparate inventory storage area that stores a second plurality of typesof items; a batch singulation station; and a control system operable to:direct the one or more robotic devices to transport a particularportable storage unit of the plurality of portable storage units to andfrom a particular induction station of the one or more inductionstations; direct induction of one or more single units of items from oneor more locations of the portable storage unit, while the particularportable storage unit is located at an induction station, into theconveyance mechanism at the particular induction station; direct picksof batches of heterogeneous items from the separate inventory storagearea; and direct induction of single units of items from the batches ofheterogeneous items picked from the separate inventory storage area intothe conveyance mechanism at the batch singulation station.
 2. Theunit-level materials handling facility of claim 1, wherein the controlsystem is operable to direct the conveyance of a stream of inductedsingle units of items from the one or more induction stations and astream of inducted single units of items from the batch singulationstation to one or more downstream processing stations via the conveyancemechanism.
 3. The unit-level materials handling facility of claim 2,wherein the control system is operable to direct the merging of thestream of inducted single units of items from the one or more inductionstations and the stream of inducted single units of items from the batchsingulation station of items prior to or at a downstream processingstation.
 4. The unit-level materials handling facility of claim 3,wherein the downstream processing station is a sorting station.
 5. Theunit-level materials handling facility of claim 3, wherein thedownstream processing station is a packing station.
 6. The unit-levelmaterials handling facility of claim 1, wherein the control system isoperable to direct, to facilitate the induction, the placement of theone or more single units of items from one or more locations of theportable storage unit into conveyance receptacles and the induction ofthe conveyance receptacles containing the one or more single units ofitems into the conveyance mechanism.
 7. The unit-level materialshandling system of claim 1, wherein the conveyance mechanism is aconveyance sorter mechanism operable to divert items off a conveyancepath under control of the control system.
 8. A system, comprising: atleast one processor; and a memory comprising program instructions,wherein the program instructions are executable by the at least oneprocessor to: direct one or more robotic devices to transport aparticular portable storage unit of a plurality of portable storageunits to and from a particular induction station of one or moreinduction stations; direct induction of one or more single units ofitems from one or more locations of the particular portable storageunit, while the particular portable storage unit is located at theparticular induction station, into the conveyance mechanism at theparticular induction station; direct picks of batches of heterogeneousitems from a separate inventory storage area; and direct induction ofsingle units of items from the batches of heterogeneous items pickedfrom the separate inventory storage area into the conveyance mechanismat a batch singulation station.
 9. The system of claim 8, wherein theprogram instructions are further executable by the at least oneprocessor to direct the conveyance of a stream of inducted single unitsof items from the one or more induction stations and a stream ofinducted single units of items from the batch singulation station to oneor more downstream processing stations via the conveyance mechanism. 10.The system of claim 9, wherein the program instructions are furtherexecutable by the at least one processor to direct the merging of thestream of inducted single units of items from the one or more inductionstations and the stream of inducted single units of items from the batchsingulation station prior to or at a downstream processing station. 11.The system of claim 9, wherein the program instructions are furtherexecutable by the at least one processor to direct the merging of thestream of inducted single units of items from the one or more inductionstations and the stream of inducted single units of items from the batchsingulation station at a sorting station.
 12. The system of claim 9,wherein the program instructions are further executable by the at leastone processor to direct the merging of the stream of inducted singleunits of items from the one or more induction stations and the stream ofinducted single units of items from the batch singulation station at apacking station.
 13. The system of claim 8, wherein the programinstructions are further executable by the at least one processor todirect, to facilitate the induction, the placement of the one or moresingle units of items from one or more locations of the portable storageunit into conveyance receptacles and the induction of the conveyancereceptacles containing the one or more single units of items into theconveyance mechanism.
 14. The system of claim 8, wherein the programinstructions are further executable by the at least one processor todirect the conveyance mechanism to operate a conveyance sorter mechanismfor diverting items off a conveyance path under control of the controlsystem.
 15. A non-transitory computer-accessible storage medium storingprogram instructions computer-executable to implement a materialshandling facility control system operable to: direct one or more roboticdevices to transport a particular storage unit of a plurality of storageunits to and from a particular induction station of one or moreinduction stations; direct induction of one or more single units ofitems from one or more locations of the particular portable storageunit, while the particular portable storage unit is located at theparticular induction station, into the conveyance mechanism at theparticular induction station; direct picks of batches of heterogeneousitems from a separate inventory storage area; and direct induction ofsingle units of items from the batches of heterogeneous items pickedfrom the separate inventory storage area into the conveyance mechanismat a batch singulation station.
 16. The non-transitorycomputer-accessible storage medium of claim 15, wherein the programinstructions are further computer-executable to direct the conveyance ofa stream of inducted single units of items from the one or moreinduction stations and a stream of inducted single units of items fromthe batch singulation station to one or more downstream processingstations via the conveyance mechanism.
 17. The non-transitorycomputer-accessible storage medium of claim 16, wherein the programinstructions are further computer-executable to direct the merging ofthe stream of inducted single units of items from the one or moreinduction stations and the stream of inducted single units of items fromthe batch singulation station prior to or at a downstream processingstation.
 18. The non-transitory computer-accessible storage medium ofclaim 16, wherein the program instructions are furthercomputer-executable to direct the merging of the stream of inductedsingle units of items from the one or more induction stations and thestream of inducted single units of items from the batch singulationstation at a sorting station.
 19. The non-transitory computer-accessiblestorage medium of claim 16, wherein the program instructions are furthercomputer-executable to direct the merging of the stream of inductedsingle units of items from the one or more induction stations and thestream of inducted single units of items from the batch singulationstation at a packing station.
 20. The non-transitory computer-accessiblestorage medium of claim 15, wherein the program instructions are furthercomputer-executable to direct, to facilitate the induction, theplacement of the one or more single units of items from one or morelocations of the portable storage unit into conveyance receptacles andthe induction of the conveyance receptacles containing the one or moresingle units of items into the conveyance mechanism.